A pilot cannot fly a plane by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300, 000 kilometers in one second. A radar set sends out short burst of radio waves. Then it receives the echoes produced when the waves bounce off objects. By determining the distance it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word "radar", in fact, gets its name from
A pilot cannot fly a plane by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300, 000 kilometers in one second. A radar set sends out short burst of radio waves. Then it receives the echoes produced when the waves bounce off objects. By determining the distance it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word "radar", in fact, gets its name from
Many people think it is safer to fly in a plane around the world than to cross a busy city street. Flying accidents are not very’ common; so when an air accident happens, the newspapers put it on the front page. Look at the newspapers headline below:
GIRL FALLS 3 000 METRES--AND LIVES TO TELL THE STORY!
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